Voltage dividers are devices which allow converting a specific voltage applied to the high-voltage terminal into a lower voltage with a specific accuracy and transformation ratio, to thus enable having a proportional measurement of the voltage applied to the high-voltage terminal. The basic operation principle of the divider is connecting a series of impedances to the voltage of a system. Thus the voltage is distributed among the impedances of the device, each impedance supporting a part of the total voltage of the system, thus the voltage of one of the impedances is proportional to the total voltage applied to the device. A resistive divider is a special case where the impedances are purely resistive, but there are also capacitive dividers where the impedances are purely capacitive.
The geometric arrangement of the elements making up the resistive divider is a key factor in the divider measurement accuracy. Furthermore, taking into account that the device must withstand high voltages the required (internal and external) insulation is necessary for its proper operation.
For internal insulation it is necessary that each resistance internally supports the part of voltage that it will be subjected to, i.e., the sum of all resistances internally meets the insulation level needed for supporting all the voltage and preventing an internal short-circuit from occurring.
For an adequate external insulation it is necessary that each resistance is externally long enough so that an external insulation malfunction (short-circuit) does not occur, i.e., meeting the insulation distances or creepage distance suitable for the voltage to be supported. Creepage distance is defined as the shortest path that an electric current must travel across the outside of an electric device between the two ends (conductors) thereof. In the case of a divider, the creepage distance of each resistance and that of the assembly must be such that it supports the total voltage applied on the divider.
For many applications, the resistances cannot be aligned (the simplest divider), since the space available is insufficient. The resistances must therefore be placed forming angles between them.